The Aldan (Sakha and Алдан) is the second-longest, right tributary of the Lena in the Sakha Republic in eastern Siberia. The river is long, of which around is navigable. It has a drainage basin of . The river was part of the River Route to Okhotsk. In 1639 Ivan Moskvitin ascended the rivers Aldan and Maya and crossed to the Ulya to reach the Sea of Okhotsk. Its basin is known for gold and for Cambrian fossils. The Aldan rises in the Stanovoy Mountains southwest of Neryungri. It flows roughly in a northeast / ENE direction south of the Lena Plateau across the Aldan Highlands, where it forms the northern border of the Sunnagyn Range. Then it flows past Aldan and through Tommot, Ust-Maya, Eldikan and Khandyga before turning northwest. In its last stretch it flanks the southern slopes of the Verkhoyansk Range and joins the Lena near Batamay. The river's main tributaries are the following: From the right Timpton Uchur Maya Khamna Allakh-Yun Khanda Tyry Eastern Khandyga Tompo Khandiga Baray Tukulan Kele Tumara Nuora From the left Amedichi Chuga Yungyuele Bilir Notora Kuoluma Amga Tatta Tanda.